The present invention relates to a method of manufacturing a GaAs (Gallium Arsenide) MES (Metal-Semiconductor) FET (Field-Effect Transistor) and, more particularly, to an improvement in a method of forming a channel layer and a gate electrode.
Since electron mobility in a GaAs substrate of a GaAs MES FET is greater than in an Si (silicon) substrate, therefore, the GaAs MES FET has become widely utilized as a high-frequency element whose operation speed must be high, or as an active element for a logic circuit IC. However, demand has increased for an improved method of manufacturing the GaAs MES FET.
Various methods of manufacturing the GaAs MES FET have been proposed. The principal procedures of the manufacturing method proposed by the present inventor and others (Japanese Patent Application No. 60-212201) will now be described, with reference to FIGS. 1A to 1C.